Automatic trip mechanism for gramophones



Dec. 19, .1967 w. MORTIMER AUTOMATIC TRIP MECHANISM FOR GRAMOPHONES Filed Feb. 12, 1965 United States Patent Ofifice 3,35 9,006 Patented Dec. 19, 1967 3,359,006 AUTOMATIC TRIP MECHANISM FOR GRAMOPHONES Edmund Walter Mortimer, Swindon, England, assignor to Garrard Engineering Limited, Swindon, England, a British company Filed Feb. 12, 1965, Ser. No. 432,169 Claims priority, application Great Britain, Feb. 21, 1964, 7,357/ 64 3 Claims. (Cl. 2741.1]l)

ABSTRACT OF THE DISCLOSURE In order to avoid the need for periodic mechanical contact between a trip-operating member of an automatic switch-off device for disc-record player and a cam repeltling the member against friction during the playing of each of the last few grooves of a record, a permanent magnet carried by the trip-operating member and a second permanet magnet rotatable with the turntable are provided which repel each other on mutual approach to restore the trip operating member to a predetermined position at the end of each revolution of the turntable during which the advance of the trip-operation member is insufiicient to produce tripping.

This invention relates to gramophones and has for an object to provide improved trip mechanism which becomes operative at the end of the play of a disc record to perform a function, such as the switching-off of a gramophone motor and/or the initiation of a so-called cycling operation for lifting the pick-up off the record and of other operations which may be desired in connection therewith such as the return of the pick-up arm onto a rest, or the initiation of a record-changer cycle or the like. It is usual to utilise for the actuation of the trip mechanism the fact that the run-out groove, which the stylus enters after completion of the play, has a considerably greater radial pitch than the maximum radial pitch employed in practice for playing grooves, and to provide for this purpose a tripcontrol member, generally a lever, which is frictionally coupled with the inward movement of the pick-up arm, at least towards the end of the play of a record, and which, when its resulting movement passes a predetermined position, engages an abutment which rotates round the turntable axis at a speed proportional to the speed of rotation of the record turntable, the mutual co-operation of this abutment and the trip-control member being utilised to trigger off the desired operation, while means are provided which when such co-operation is not produced by a predetermined amount of rotation, generally approximately one full revolution, of the turntable, return the trip-control member to a position at which its distance from the path of the abutment is greater than the amount of its feed produced by a recording groove of maximum pitch during such part of a revolution.

The present invention has for an object to provide a trip mechanism of the kind specified in which this periodic return movement of the trip-control member is effected without physical contact. According to the present invention the return movement of the first control member is effected by a magnetic circuit the flux-conducting path of which includes one element which participates in the rotation of the abutment and another element which is movable with the trip control member so that the magnetic circuit becomes operative periodically to remove the trip-control member by the desired amount from the position producing 'i ts tripping co-operation with the rotary abutment. Preferably magnetic repulsion is used for the purpose in question, and two permanent magnets are preferably used for the purpose, one of these magnets being carried by the trip-control member while the other rotates with the said abutment to become operative once during each revolution of the record turntable unless the trip-control member has previously come into tripping co-operation with the rotary abutment. The features of the invention can be incorporated, replacing the mechanical return means for the trip-control element, in the automatic trip mechanism described and claimed in our USA. Patent No. 2,757,006 or, in the case of a record player having no automatic record-changing mechanism, in the device described in our co-pending British patent application No. 24,738/63,

One embodiment of the invention is illustrated by Way of example in the accompanying drawing, in which FIGURE 1 is a plan view showing the trip mechanism as it would appear with the turntable removed,

FIGURE 2 is a fragmentary section on line 2-2 of FIGURE 1, and

FIGURE 3 is a fragmentary section on line 3-3 of FIGURE 1.

Referring now to the drawing, as the stylus of a gramophone disc-record player equipped with the trip mechanism moves inwardly of the record towards the end of its play, a trip-operating member, represented by a lever 1, is moved inwardly by a friction plate 2 which, by means of a pin 3, is coupled to the pick-up arm 19 of the disc record player, preferably through a lost-motion device so as to avoid imposing any restraint on the inward movement of the pick-up arm until the last few playing grooves of the record disc are reached. The trip-operating lever 1 is so connected to a pivot 10 as to be free not only to move about the pivot 10 in a horizontal plane but also to have its opposite end 1A lifted from its normal plane, thereby raising an arm 17 of a trip mechanism 18 pivoted in the stationary part of the record player or changer. Such upward movement of the arm 17 is utilised to initiate the next record-changing cycle, stop the player, or initiate some other desired operation. Normally the lever is held in its normal horizontal position, and is at the same time coupled with the friction plate 2 by a friction pad 12 which projects from the lower side of the lever 1 and is supported on the friction pad 2,. Lifting the lever 1 is effected at the end of the play of a record by a face cam 14 provided on a member 15 which projects from the spindle structure 7 of the gramophone turntable. The face cam 14 co-operates with a ramp 13 formed on a clip 4 which is riveted to the underside of the lever 1.

In order to prevent the lever 1 from moving towards the axis of the turntable spindle structure 7 sufiiciently to engage the face cam 14 until the pick-up stylus has reached the steep-pitch running-out groove of the record, a short bar magnet 5 is clamped to the arm 1 by the clip 4, and a second bar magnet 6 is similarly clamped to the spindle structure 7 by a clip bracket 8, the arrangement being such that the axes of the two magnets 5 and 6 lie in a common horizontal plane and that when, during the rotation of the turntable, the magnet 6 assumes the position illustrated in FIGURE 1, equal poles of the two magnets 5 and 6 face each other. A repulsion force is thus produced which moves the lever 1 away from the axis of the turntable to a distance at which the opposing faces of magnets 5 and 6 are spaced by more than the maximum amount of approach movement of the lever 1 produced by the advance of the pick-up arm when traversing a complete turn of a recording groove of maximum pitch. When however the stylus enters the running-out groove of a record, whose pitch is a multiple of the maximum pitch of a recording groove, the lever 1 approaches the spindle 7 sufliciently during a single revolution of the turntable to bring the ramp 13 into engagement with the face cam 14 on member 15 which, as can be seen in FIGURE 1, is displaced about the axis of spindle 7 relative to the magnet 6 in such direction that the face carn will engage the ramp 13, and thus lift the lever 1 and cause the trip mechanism 18 to be actuated by its arm 17, before the magnet 6 encounters the magnet of the arm.

Preferably the spindle structure also includes a striker cam 16 which is arranged above the magnet 5 and which, after the trip mechanism has been actuated, pushes the lever 1 back horizontally, out of engagement with the face cam 14, thus avoiding unnecessary repeated lifting and dropping of the trip-operating lever 1.

The trip mechanism 18 has only been illustrated symbolically, and it will be readily appreciated that it may assume a variety of conventional or convenient forms, including that illustrated in our above-mentioned U.S.A. Patent No. 2,757,006, and it will also be appreciated that the actual tripping operation may be carried out, iftdesired, without lifting of the trip operating member, for example in the manner described in our co-pending British patent application No. 24,738/ 63.

What I claim is:

1. In a disc-record player having a rotatable turntable for supporting a grooved disc record to be played, driving means for rotating said turntable about an axis, and a pickup device movable from a starting position towards the turntable axis in co-operation with the groove of such record, the combination comprising an abutment arranged for joint movement with the turntable about said axis and spaced from said axis, and means operable by said abutment to arrest said turntable-driving means, said arresting means being movable from a normal position clear of the path of said abutment into an operating position in the path of said abutment, frictional coupling means operative, at least during a terminal part of such movement of the pick-up device, to yieldingly move said arresting means towards its operative position, a first magnet element participating in such movement of the arresting means towards its operative position, and a second magnet element participating in the movement of the abutment about the turntable axis, said magnet elements being so arranged as to return by magnet repulsion, when meeting each other after the arresting means has approached the operative position beyond a predetermined distance, said arresting means to the said distance from the operative position, said distance being greater than the amount of the approach movement of the arresting means towards the operative position produced by one turn of a standard recording groove but less than that produced by a turn of a standard running-out groove, and the angular position of said second magnet element relative to said abutment means about the turntable axis being such as to ensure, when the arresting means is in its operative position, engagement thereof with said abutment to arrest the drive before the mutual approach of the magnet elements is sufficient to produce such repulsion of the arresting means.

2. The combination as claimed in claim 1, wherein each of said magnet elements includes a permanent magnet.

3. The combination as claimed in claim 2, wherein the record player includes a base plate relative to which the turntable is mounted for rotation about a vertical axis, and the pick-up element includes a pick-up arm mounted for pivotal movement about a vertical axis outside the turntable, the arresting means including a trip-control member in the form of a lever movable into engagement with said abutment member, said permanent magnets being respectively housed in said lever and in said abutment structure, said turntable being mounted on a spindle structure for common rotation with it, and said spindle structure including being equipped with abutment structure which includes said rotary abutment.

References Cited FOREIGN PATENTS 447,228 4/1949 Italy.

LEONARD FORMAN, Primary Examiner.

F. DAMBROSIO, Assistant Examiner. 

1. IN A DISC-RECORD PLAYER HAVING A ROTATABLE TURNTABLE FOR SUPPORTING A GROOVED DISC RECORD TO BE PLAYED, DRIVING MEANS FOR ROTATING SAID TURNABLE ABOUT AN AXIS, AND A PICKUP DEVICE MOVABLE FROM A STARTING POSITION TOWARDS THE TURNTABLE AXIS IN CO-OPERATION WITH THE GROOVE OF SUCH RECORD, THE COMBINATION COMPRISING AN ABUTMENT ARRANGED FOR JOINT MOVEMENT WITH THE TURNTABLE ABOUT SAID AXIS AND SPACED FROM SAID AXIS, AND MEANS OPERABLE BY SAID ABUTMENT TO ARREST SADI TURNTABLE-DRIVING MEANS, SAID ARRESTING MEANS BEING MOVABLE FROM A NORMAL POSITION CLEAR OF THE PATH OF SAID ABUTMENT INTO AN OPERATING POSITION IN THE PATH OF SAID ABUTMENT, FRICTIONAL COUPLING MEANS OPERATIVE, AT LEAST DURING A TERMINAL PART OF SUCH MOVEMENT OF THE PICK-UP DEVICE, TO YIELDINGLY MOVE SAID ARRESTING MEANS TOWARDS ITS OPERATIVE POSITION, A FIRST MAGNET ELEMENT PARTICIPATING IN SUCH MOVEMENT OF THE ARRESTING MEANS TOWARDS ITS OPERATIVE POSITION, AND A SECOND MAGNET ELEMENT PARTICIPATING IN THE MOVEMENT OF THE ABUTMENT ABOUT THE TURNTABLE AXIS, SAID MAGNET ELEMENTS BEING SO ARRANGED AS TO RETURN BY MAGNET REPULSION, WHEN MEETING EACH OTHER AFTER THE ARRESTING MEANS HAS APPROACHED THE OPERATIVE POSITION BEYOND A PREDETERMINED DISTANCE, SAID ARRESTING MEANS TO THE SAID DISTANCE FROM THE OPERATIVE POSITION, SAID DISTANCE BEING GREATER THAN THE AMOUNT OF THE APPROACH MOVEMENT OF THE ARRESTING MEANS TOWARDS THE OPERATIVE POSITION PRODUCED BY ONE TURN OF A STANDARD RECORDING GROOVE BUT LESS THAN THAT PRODUCED BY A TURN OF A STANDARD RUNNING-OUT GROOVE, AND THE ANGULAR POSITION OF SAID SECOND MAGNET ELEMENT RELATIVE TO SAID ABUTMENT MEANS ABOUT THE TURNTABLE AXIS BEING SUCH AS TO ENSURE, WHEN THE ARRESTING MEANS IS IN ITS OPERATIVE POSITION, ENGAGEMENT THEREOF WITH SAID ABUTMENT TO ARREST THE DRIVE BEFORE THE MUTUAL APPROACH OF THE MAGNET ELEMENTS IS SUFFICIENT TO PRODUCE SUCH REPULSION OF THE ARRESTING MEANS. 